An off-duty deputy U.S. marshal was found guilty of obstruction of justice on Thursday for lying to LAPD homicide detectives in order to justify killing a man. After striking his wife in public and gunning down a stranger who defended her, U.S. Marshal Matthew Itkowitz provided misleading statements to his superior and the homicide detectives investigating the shooting. Unbeknownst to the drunken deputy marshal, a nearby surveillance camera recorded the incident and discredited his lies.

After dining at a Mexican restaurant with his wife and drinking too many shots of tequila on the evening of March 5, 2008, off-duty U.S. Marshal Matthew Itkowitz and his wife were walking home discussing marital problems when he began physically abusing her. According to a district attorney report, Itkowitz struck his wife and pushed her before she ran toward a nearby tattoo parlor and asked for help. Ryan Gonzalez, the manager of the tattoo parlor, confronted Itkowitz and asked, “Why are you yelling at the lady? Why are you treating the lady like that?”

Although the surveillance video does not capture the beginning of the fight, the footage does show Gonzalez knocking down Itkowitz twice before motioning for him to leave. When Itkowitz refuses to leave, Gonzalez follows him into the alley and appears to pull a gun out of his pocket. After briefly pointing the gun at Itkowitz, Gonzalez places the pistol back into his pocket while ordering Itkowitz to leave again.

As Gonzalez turns around and begins walking away, Itkowitz pulls out a Glock .40-caliber pistol and hides it behind his right leg. When Gonzalez motions for him to leave again, Itkowitz fires at him even though Gonzalez never reaches for his own gun. According to prosecutors, Itkowitz shot Gonzalez five times, including at least two bullets in the back as Itkowitz chased him down the alley.

While hiding under a car, the deputy marshal’s wife, Alexandra Itkowitz, asked a friend to call the police. On the recorded 911 tape, a male voice told the dispatcher, “From what I heard, she was crying hysterically and she says that she saw him shoot somebody in cold blood. And because she knows that he can kill somebody else like that, that he’s going to kill her.”

When LAPD officers arrived at the scene, they found Alexandra hiding under a parked car. In order to justify the killing, Itkowitz told the homicide detectives that he began shooting Gonzalez a split-second after Gonzalez punched him. Itkowitz later informed his supervisor that he had been “attacked by two Hispanics” attempting to rob him in an alley.

But surveillance footage revealed that Itkowitz had lied to his supervisor and the LAPD homicide detectives. According to the video, Itkowitz did not begin shooting Gonzalez until about a minute after their physical altercation. And two Latino men did not attack Itkowitz while attempting to rob him.

Although the Los Angeles County district attorney’s office declined to prosecute Itkowitz in 2010, a federal grand jury indicted him on civil rights and obstruction charges in August 2012. On Wednesday, U.S. District Judge Philip Gutierrez tossed out the two civil rights charges against Itkowitz because federal prosecutors failed to provide enough evidence to convict him of depriving Gonzalez of his civil rights under color of law.

“After he shot Ryan Gonzalez, the defendant tried to cover up what he had done,” Assistant U.S. Attorney Lawrence Middleton told jurors during closing arguments. “He described a shooting that looked nothing like what you saw.”

On Thursday, the jury found Itkowitz guilty of obstruction of justice for making misleading statements to the LAPD homicide detectives, but they found him not guilty of obstructing justice when Itkowitz lied to his supervisor about the two Latino men attempting to rob him. He faces a maximum sentence of 20 years in federal prison.